Fire fighting boom assembly for service vessel

ABSTRACT

An extendable utility boom assembly for assisting fire-fighting operations performed from a semi-submersible service vessel upon an offshore platform is disclosed. The boom assembly is moved to operating position by means of a carriage assembly which is mounted for movement along a track secured to the deck of the service vessel. Orientation of the boom assembly in azimuth and pitch is provided by a supporting frame which is pivotally mounted on the carriage assembly for angular movement through a horizontal plane, and a boom housing which is pivotally mounted on the supporting frame for angular movement through a vertical plane. An elongated utility boom is supported by roller bearing elements for axial movement through the boom housing. A first linear actuator is interconnected between the carriage assembly and supporting frame for displacing the supporting frame through the horizontal plane. A second linear actuator is interconnected between the boom housing and the carriage assembly for displacing the boom housing through the vertical plane, and a third linear actuator is interconnected between the boom and the boom housing for displacing the boom along the axis of the boom housing. The elongated utility boom is characterized by a polygon in transverse section, with the aft section of the boom being substantially constant in cross section along its length, and the forward section of the boom being tapered in cross section along its length. This particular configuration provides a high strength-to-weight ratio and can withstand the high operating temperature encountered during fire fighting operations. A hydraulic utility claw assembly is mounted on the end of the extendable boom for forcibly removing structural components from the offshore platform during a firefighting operation. The utility claw assembly is characterized by a movable jaw which is coupled to a drawbar by a linkage arrangement which provides substantialy constant shearing force throughout the closure range of the movable jaw.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related generally to utility service equipment for assisting firefighting operations, and in particular to an extendable boom assembly which may be operated from the service deck of a semi-submersible service vessel for assisting offshore platform firefighting operations.

2. Description of the Prior Art

As energy demands increase, so does the need to explore and produce petroleum from offshore areas in deep and rough waters. Of vital concern to such offshore petroleum production operations is the need for adequate measures to be taken to minimize the effects of blowouts, fires and spills. There is a continuing interest in the advancement of concepts and equipment to adequately handle such offshore disasters in the rougher and deeper waters of the world.

Of particular concern is the possibility of a fire occurring on an offshore platform in relatively deep and rough waters. Such fires burn so intensely that the offshore derrick and associated equipment collapse and fuse together in a molten mass around the fire. In order to extinguish the fire, it is necessary to remove the collapsed structure to make room for the placement of an explosive charge which is subsequently detonated to blow out the fire. Because such fires burn so intensely, for example at temperatures of 2000° Fahrenheit and above, it is not safe for personnel or a service vessel to approach the platform closely enough to carry out firefighting operations.

According to a recent invention, a semi-submersible service vessel has been developed which is capable of assisting firefighting operations on offshore platforms. Such a vessel is disclosed and claimed by the co-pending U.S. Application Ser. No. 845,831 filed Oct. 31, 1977, and entitled "Self-Propelled Semi-Submersible Service Vessel". The object of the present invention is to disclose the proprietary details of an extendable utility boom assembly which can be operated safely and effectively from the deck of such a service vessel for assisting firefighting operations carried out on an offshore platform.

SUMMARY OF INVENTION

An extendable utility boom assembly for assisting firefighting operations performed upon an offshore platform is disclosed. The extendable boom assembly is particularly well suited for operation from a semi-submersible service vessel of the type including a service deck from which marine services operations may be performed. In its broadest aspects, the extendable fire boom assembly includes an elongated truss which is extendable relative to the deck, and an elongated boom which is extendable relative to the truss. A track is secured to the deck of a service vessel for guiding the movement of the extendable truss from a stowed position to an operating position. A track is secured to the truss for guiding the movement of a carriage assembly along the length of the truss. Orientation of the boom assembly in azimuth and pitch is provided by a supporting frame which is pivotally mounted on the carriage assembly for angular movement through a horizontal plane, and a boom housing which is pivotally mounted on the supporting frame for supporting the elongated boom in angular movement through a vertical plane. The trunnion includes wall portions defining a central axial passageway in which an aft boom section is disposed and from which a forward boom section projects for reaching a desired location on an offshore platform. A first linear actuator is interconnected between the carriage assembly and supporting frame for displacing the supporting frame through the horizontal plane. A second linear actuator interconnects the carriage assembly and boom housing for displacing the elongated boom through the vertical plane. A third linear actuator interconnects the boom housing and boom for displacing the utility boom along the axis of the boom housing.

According to an important feature of the invention, the elongated utility boom comprises a number of elongated panels having side portions assembled together in edge abutting relation thereby defining a panel assembly which is characterized by a polygon in transverse section. The elongated boom comprises a first boom section which is substantially constant in cross section along its length and a second boom section which is tapered in cross section along its length. It has been determined that this particular structural arrangement has a high strength-to-weight ratio for handling heavy loads, and its polygon configuration provides rapid and uniform heat dissipation for operation in high temperature environments.

According to yet another important feature of the invention, a utility claw assembly is mounted on an end portion of the elongated boom for rotation about the longitudinal axis of the boom. The utility claw includes a fixed jaw, a moveable jaw having a lever portion mounted for pivotal movement relative to the fixed jaw, and a moveable draw bar coupled to the claw assembly for displacing the moveable jaw relative to the fixed jaw. A draw tube is disposed within the utility boom and mechanically connects the moveable jaw to a linear actuator for displacing the moveable jaw relative to the fixed jaw. The draw tube is also coupled to a rotary actuator for displacing the utility claw assembly about the longitudinal axis of the boom assembly. An improved linking mechanism is provided for efficiently transforming the linear motion of the draw bar into rotary movement of the moveable jaw as it transmits a shearing force to an object seized between the fixed and moveable jaws.

The novel features which characterize the invention are defined by the appended claims. The foregoing and other objects, advantages and features of the invention will hereinafter appear, and for purposes of illustration of the invention, but not of limitation, an exemplary embodiment of the invention is shown in the appended drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a port profile elevation view of a semi-submersible service vessel on which an extendable fire boom assembly constructed according to the teachings of the present invention is mounted;

FIG. 2 is a partial plan view of the main deck of the semi-submersible service vessel shown in FIG. 1 in which the extendable fire boom assembly is disposed in a stowed position;

FIG. 3 is a plan view similar to FIG. 2 in which the extendable truss of the fire boom assembly is disposed in operating position;

FIG. 4 is a port profile elevation view similar to FIG. 1 in which the semi-submersible service vessel is moored adjacent an offshore platform and the extendable fire boom assembly is fully extended in operating position for assisting a firefighting operation;

FIG. 5 is a side elevation view of the extendable fire boom assembly of the invention;

FIG. 6 is a top plan view of the extendable fire boom assembly shown in FIG. 5;

FIG. 7 is an aft elevation view, partly in section of the extendable fire boom assembly of FIG. 5;

FIG. 8 is a sectional view taken along the lines VIII--VIII of FIG. 7;

FIG. 9 is an elevation view, partly in section, of the aft boom section of the extendable fire boom;

FIG. 10 is a view similar to FIG. 9 which illustrates the construction of the forward boom section of the extendable fire boom;

FIG. 11 is an elevation view which illustrates the construction of the utility claw assembly which is mounted on the forward boom section of FIG. 10;

FIG. 12 is a plan view of the utility claw assembly shown in FIG. 11; and,

FIG. 13 is an end elevation view of the trunnion which supports the extendable boom of FIGS. 9 and 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the description which follows, like parts are marked throughout the specification and drawing with the same reference numerals respectively.

Referring now to the drawing, and in particular to FIGS. 1-4, the invention is shown in combination with a self-propelled semi-submersible column stabilized service vessel 10 the general features of which are described in detail in the co-pending U.S. Application Ser. No. 845,831, filed Oct. 31, 1977, entitled "Self-Propelled Semi-Submersible Service Vessel", which is hereby incorporated by reference. The service vessel 10 is a twin-hulled, column stabilized, self-propelled semi-submersible type utility service vessel which is properly constructed and equipped for extended operations in relatively deep and rough waters such as the North Sea production fields.

An extendable fire boom assembly 12 is shown in a stowed position upon a service desk 14 in FIGS. 1 and 2, in an intermediate position in FIG. 3, and in a fully extended operating position adjacent an offshore platform 16 in FIG. 4. The extendable boom assembly 12 includes an extendable truss 18, a fire vehicle 20 and an extendable fire arm or boom 22. The extendable truss 18 is mounted for guided movement upon parallel rails 24 which are secured to the service desk 14 for supporting the extendable truss over the forward edge of the service vessel 10. The extendable truss 18 comprises a number of cross-brace members 25 in tension and compression according to conventional construction. Parallel tracks 27 (FIGS. 5 and 7) mounted along the top of the extendable truss 18 supports movement of the fire vehicle 20 relative to the extendable truss. The extendable truss 18 is propelled across the service deck 14 by means of hydraulic skid jacks 26, and the fire vehicle 20 is propelled by means of a hydraulic drive assembly as discussed below.

According to a preferred procedure for extending the boom assembly 12, the truss 18 is extended along the tracks 24 by operation of the hydraulic skid jacks 26 to a desired position forward as shown in FIG. 3. Tie-down bolts (not shown) are installed through a skid girder flange at the aft end. Thereafter, the fire boom 22 is lifted from its stowed position as shown in FIG. 2 by means of a revolvable crane 28 and is placed in position and bolted in place on the fire vehicle 20. After the initial setup, the fire boom 22 is fully retracted to the position shown in FIG. 3 before changing the position of the extendable truss 18.

The extendable boom assembly 12 is designed to operate extended thirty to eighty feet forward of the bow. After the extendable truss 18 has been jacked forward along the tracks 24 to its desired position, and has been bolted in place, the fire vehicle 20 may be moved along tracks 27 toward the forward end of the fire boom. The fire vehicle 20 can be operated at any position along the truss 18. The extendable fire boom assembly is cooled at all times with a water spray when it is near a fire, as is shown in FIG. 4.

According to an important feature of the invention, the extendable fire boom 22 is provided with a utility claw assembly 30 which is attached to the remote end of the boom for forcibly removing pieces of the burning or damaged structure, for positioning control valves, or for placing explosive charges. When using the fire boom assembly 12 for positioning explosives, the claw is preferably removed from the end of the boom 22 and a bar (not shown) is welded onto the end of the arm to support the explosive charge.

Referring now to FIGS. 5, 6, 7 and 8, the construction of the extendable fire boom assembly 12 is illustrated in detail. The extendable truss includes the rails 27 for guiding the movement of a trolley or carriage assembly 32. The rails 27 are preferably provided with teeth 34 which are engaged by a rotating drive wheel 36 carried on the trolley 32. Motion of the carriage assembly 32 is stabilized by means of upper and lower rowers 38, 40 respectively, and by means of side load rollers 42. The stability rollers are mounted on a trolley weldment 44 on which a support frame 46 is mechanically coupled for pivotal rotation through a horizontal plane to permit movement of the extendable fire boom 22 from one azimuth position to another. The support frame 46 is mounted on a gear weldment 48 on which a circular gear having teeth 50 has been machined. The gear plate weldment 48 is supported for rotational movement upon the trolley weldment 44 by means of a number of ball bearings 52 which permit rolling movement within circular raceways 54, 56 which are aligned to define a continuous annular raceway extending around the gear plate 48 as illustrated in FIG. 8 of the drawing.

A boom housing 58 is pivotally supported on the support frame 46 by trunnion shafts 60, 62 for angular movement through a vertical plane to permit the pitch of the extendable fire boom 22 to be varied in relation to the support frame 46. A pair of hydraulic linear actuators 64, 66 are connected intermediate the support frame 46 and boom housing 58 for controlling its angular movement as it is displaced through its vertical plane of rotation. The support frame 46 is likewise displaced through its horizontal plane of rotation by means of a pair of hydraulic linear actuators 68, 70 which are operably connected to first and second rotate drive assemblies 72, 74 each of which having teeth 76 meshed with the teeth 50 of the gear weldment 48 for controlling the azimuth position of the support frame 46 relative to the carriage assembly 32. Pressurized hydraulic fluid for actuating the linear and rotary actuators is conveyed by means of a hose chain assembly 78A. A hose chain assembly 78B is connected to the carriage assembly 32 and supplies hydraulic fluid to hydraulic drive equipment such as a trolley drive assembly 80 which is powered by a hydraulic motor 82.

Referring now to FIGS. 5, 7 and 13, the extendable boom 22 includes an aft boom section 22A and a forward boom section 22F. The utility boom assembly 22 is characterized by a polygon in cross-section, as can best be seen in FIG. 13, and in particular is formed by eight elongated panels 22B, C, D, E, G, H, I and J which are assembled together in edge abutting relation to define an octagon in transverse section. The aft section 22A is sealed by an end plate 83 and has a substantially constant diameter as measured from the centers of diametrically opposite panels. The forward section 22F is tapered in diameter along its length. As previously discussed, because of its heat dissipation properties and its high strength-to-weight ratio, this particular configuration is ideally suited for handling large loads in a high temperature environment. Also, according to this particular arrangement, the abutting side portions enclose and protect control apparatus for the utility claw assembly 30 in an interior chamber 84 (FIGS. 9 and 10).

The diameter of the aft boom section 22A is substantially constant and is supported for axial movement through the boom housing 58 by means of roller bearing elements 86A-86D which engage bearing plates 87A-87D (FIG. 13) on diametrically opposite side panels of the first boom section 22A and a second group of roller bearing elements 86E-86H (FIGS. 5, 6) which engage the bearing plates 87A-87D on opposite side panels of the aft boom section 22A at a location on the aft boom section which is axially spaced relative to the first roller bearing elements 86A-86D. This arrangement stabilizes axial movement of the fire boom 22 through the boom housing 58. The extendable fire boom 22 is moveable relative to the boom housing by means of a hydraulic linear actuator 88 as shown in FIG. 7 and which can best be seen in FIG. 9 of the drawing. The hydraulic linear actuator 88 includes a rod mount 90 which is attached to the boom housing 58 and a hydraulic cylinder 92 which is secured to one of the side panels of the aft boom section 22A as shown in FIG. 13.

An important capability of the extendable fire boom assembly 12 is its ability to retrieve equipment from the deck of an offshore platform. To carry out this function, the boom assembly 12 includes a winch 94 secured to the boom housing and a sheave 96 secured to the remote end of the forward section 22F of the extendable boom 22. A hoist line 99 includes a first end portion coupled to the winch 94 and a second end portion coupled in reeved engagement with the sheave 96. A hook 100 is attached to the second end portion of the hoist line 98 for lifting a load in response to actuation of the hydraulic winch 94. This arrangement can be used to good advantage for retrieving valuable equipment from the deck of an offshore platform which is threatened by fire or some other impending disaster.

According to an important feature of the invention, the utility claw assembly 30 is attached to the remote end of the forward boom section 22F as shown in FIGS. 5, 6 and 10. The claw assembly 30 is coupled to the end of the forward boom section 22F by means of sleeve bearing elements 102 which permit rotational movement of the claw assembly 30 about the longitudinal axis 104 of the boom assembly 22 as shown in FIG. 4 of the drawing.

The utility claw assembly 30 includes a fixed jaw 106 and a moveable jaw 108 having a lever portion 110 mounted for pivotal movement relative to the fixed jaw 106 about a pivot pin 112. A moveable draw bar 114 is coupled to the claw assembly 30 for displacing the moveable jaw relative to the fixed jaw.

A draw tube 116 is mounted within the central chamber 84 of the boom 22 for axial displacement and rotation with respect to the longitudinal axis 104 of the boom. The draw tube has a forward end portion 116F connected to the draw bar 114 and an aft end portion 116A coupled to a draw rod 118. The draw tube serves as an intermediate element for transmitting axial and rotational movement to the utility claw assembly 30. A rotary actuator 122 is coupled to the draw rod 118 for driving the draw tube and utilty claw assembly in rotation about the longitudinal axis 104. The rotary actuator 122 is of conventional hollow shaft construction for permitting the draw rod 118 and draw tube 116 to be driven in rotation about the longitudinal axis 104 while simultaneously permitting axial displacement of the draw tube 116 and draw rod 118 with respect to the rotary actuator 122 in response to the operation of the linear actuator 120.

Turning now to FIGS. 11 and 12, the construction details of the utility claw assembly 30 are illustrated. The utility claw assembly 30 comprises generally a support arm 124 having an elongated shank 126. A straight slot 128 extends axially through the shank with the fixed jaw 106 projecting from one end of the shank and having a curved slot 130 extending along a curved path through the fixed jaw 106. The lever portion 110 of the moveable jaw 108 is pivotally connected to the support arm by the pin 112. The draw bar 114 has an aft end portion 114A coupled to the draw tube 116 and a forward end portion 114F disposed for movement along the straight slot 128.

A link bar 132 has an aft end portion 132A disposed for movement along the straight slot 128 and a forward end portion 132F disposed for movement along the curved slot 132. A bearing pin 134 is disposed within the straight slot 128 and pivotally connects the forward end portion 114F with the aft end portion 132A of the link bar 132. A bearing pin 136 is similarly disposed within the curved slot 130 and pivotally connects the forward end portion of the link bar 132F with the end portion of the link bar 132. It is preferred that the curved slot 130 follow an arc of constant radius having an origin of curvature which is concentric with the pivotal axis of the moveable jaw. It has been determined that this linkage arrangement permits a force transmitted by the draw bar 114 to be converted into a substantially constant rotary shear force as the moveable jaw is driven in rotational movement.

Since the utility claw assembly 30 is used for clearing structure from an offshore platform, a shear blade 138 is attached to the fixed jaw 106 with front and rear shear blades 140, 142 being attached to the moveable jaw 108. The function of the upper shear blades 140, 142 is to transmit a shearing force in response to a force conducted from the draw tube through the draw bar, link bar and lever. The function of the lower shear blade 138 which is mounted on the fixed jaw 106 is to transmit a reaction force in response to shear loading of an object seized between the fixed and moveable jaws.

Referring to FIG. 12, according to a preferred embodiment, the fixed jaw is symmetrical with respect to the longitudinal axis 104 and the support shank 126 is bifurcated with respect to the axis of symmetry. In this arrangement, the bifurcated shank 126 includes first and second shank portions 126A, 126B which are laterally spaced and disposed in parallel with each other, with the moveable jaw 108 and draw bar 114 being mounted in the space lying between the shank portions 126A and 126B.

Although preferred embodiments of the invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims. 

What is claimed is:
 1. A utility claw assembly comprising, in combination:a support arm having an elongated shank, a fixed arcuate jaw projecting from one end of the shank, a first slot extending axially through the shank, and a second slot extending along a curved path through the fixed jaw; a moveable arcuate jaw having a lever portion pivotally mounted to the support arm; a draw bar disposed on one side of the shank for axial movement along the first slot; a link bar disposed on the opposite side of the shank, the link bar having a first end portion disposed for movement along the first slot and a second end portion disposed for movement along the second slot; a first bearing element disposed within the first slot pivotally connecting the draw bar to the first end portion of the link bar; and, a second bearing element disposed within the second slot pivotally connecting the second end portion of the link bar to the lever arm.
 2. The utility claw assembly as defined in claim 1, the combination including:a first shear blade mounted on the moveable jaw for transmitting a shearing force from the draw bar through the link bar and lever; and, a second shear blade mounted on the fixed jaw for transmitting a reaction force in response to shear loading of an object seized between the fixed and moveable jaws.
 3. The utility claw assembly as defined in claim 1, the second slot defining an arc of constant radius having an origin of curvature concentric with the pivotal axis of the moveable arcuate jaw.
 4. The utility claw assembly of claim 1, said fixed jaw having a longitudinal axis of symmetry, said support shank being bifurcated with respect to said axis of symmetry, said bifurcated shank including first and second shank portions laterally spaced and disposed in parallel with each other, said moveable jaw and draw bar being pivotally mounted intermediate said shank portions, said link bar pivotally interconnecting the lever arm of said moveable jaw with said draw bar.
 5. A utility boom assembly comprising, in combination:a carriage assembly; a supporting frame mounted on the carriage assembly for angular movement in a horizontal plane; a first linear actuator mechanically interconnecting the carriage assembly and supporting frame for driving the carriage assembly in the horizontal plane; a boom housing pivotally mounted on the supporting frame for angular movement in a vertical plane; a second linear actuator interconnecting the carriage assembly and trunnion for displacing the boom housing about its pivotal axis in the vertical plane; an elongated utility boom including a first boom section disposed for axial movement through the boom housing and a second boom section projecting axially out of the boom housing; a third linear actuator interconnecting the boom housing and utility boom for displacing the utility boom along the axis of the boom housing; a utility claw assembly mounted on the second boom section for rotation about the longitudinal axis of the boom, the utility claw including a fixed jaw, a movable jaw having a lever portion mounted for pivotal movement relative to the fixed jaw, and a movable draw bar coupled to the claw assembly for displacing the movable jaw relative to the fixed jaw; a draw tube disposed within the utility boom for axial displacement and rotation with respect to the longitudinal axis of the boom, the draw tube having a first end portion connected to the draw bar and having a second end portion for transmitting axial and rotational forces; a linear actuator coupled intermediate the utility boom and draw tube for displacing the draw tube along the longitudinal axis of the utility boom; and a rotary actuator coupled intermediate the utility boom and draw tube for driving the draw tube and utility claw assembly in rotation about its longitudinal axis.
 6. The utility boom assembly as defined in claim 5, the utility claw assembly comprising:a support arm having an elongated shank and straight slot extending axially through the shank, the fixed jaw projecting from one end of the shank and having a curved slot extending along a curved path through the fixed jaw, the lever portion of the movable jaw being pivotally mounted to the support arm; a draw bar disposed on one side of the shank having a first end portion coupled to the draw tube and a second end portion disposed for movement along the straight slot; a link bar disposed on the opposite side of the shank having a first end portion disposed for movement along the straight slot and a second end portion disposed for movement along the curved slot; a first bearing element disposed within the straight slot pivotally connecting the second end portion of the draw bar to the first end portion of the link bar;and, a second bearing element disposed within the curved slot pivotally connecting the second end portion of the link bar to the lever arm.
 7. The utility boom assembly of claim 6, the curved slot defining an arc of constant radius having an origin of curvature coincidental with the pivotal axis of the movable jaw.
 8. The utility claw assembly as defined in claim 6, the combination including:a first shear blade mounted on the movable jaw for transmitting a shearing force in response to a force conducted from the draw tube through the draw bar, link bar and lever; and, a second shear blade mounted on the fixed jaw for transmitting a reaction force in response to shear loading of an object seized between the fixed and movable jaws. 